A 32-year-old Blair Athol man has been charged with aggravated assault to cause harm and assault police after allegedly knocking unconscious another man in the Adelaide CBD early Thursday morning.

South Australian police had received reports of a disturbance on Rundle Street at around 2.45am where the victim had been assaulted. He was treated at the scene by SA Ambulance and taken to the Royal Adelaide Hospital with non-life threatening injuries.

The ABC reports that a fight was believed to have broken out over a taxi outside the Exeter Hotel, a university bar close to the University of Adelaide.

The 32-year-old who was arrested is bailed to appear in court in April, with police now looking for two other men involved in the fight.